scientific_item.py: Guard for doi being empty string

asseeibot/models/wikimedia/wikidata/scientific_item.py

@@ -144,8 +144,6 @@ def __lookup_via_hub__(self) -> None:
                 raise ValueError("doi was empty string")
             logger.info("Using DOI from Crossref to lookup in Hub")
             self.__call_the_hub_api__(doi)
-        if self.doi == "":
-            raise ValueError("doi was empty string")
         if not self.found_in_wikidata:
             logger.info("Using DOI from Wikipedia to lookup in Hub")
             self.__call_the_hub_api__(self.doi.value)